The present invention relates generally to methods and devices used to form an operating cavity between adjacent tissue layers of a patient More specifically, the present invention relates to devices which may be percutaneously inserted into the body through a small diameter cannula and expanded between adjacent layers of tissue to provide an operating cavity in registry with an operating area and to provide a prosthesis to facilitate, for example, groin herniorrhaphy.
Groin herniorrhaphy is among the oldest and most common surgical procedures performed. Unfortunately, the average operative result is beset by a period of discomfort with resultant disability. Techniques have been developed, such as laparoscopic herniorrhaphy, with the intent to reduce morbidity and recurrence rates. Most trials, however, have noted only a moderate improvement in the pain and disability associated with the procedure. Further, the added cost of equipment, the need for general anesthesia, and the additional operating room time required for this procedure indicates that it is less than ideal. There continues to be a need in general surgery for a procedure that can effectively address all the considerations of cost, disability, and hernia recurrence for patients with an inguinal hernia.
Failure of the transversalis fascia to retain the peritoneum from penetrating the myopectineal orifice is the fundamental cause of all groin hernias. Historically, hernias were repaired by stretching the transversus abdominis tendon across the myopectineal orifice and suturing it to the inguinal ligament. This technique and its current modifications rely upon the surgical approximations of edges of the defect to cover the myopectineal orifice. Such a technique, however, results in a distortion of the groin anatomy which creates stress on both the suture upon which the hernia repair is dependent and on the tissue planes that have already demonstrated their inherent weakness by the presence of a hernia. It is believed that the tension placed on the suture line as a result of the unnatural approximation of the tissues leads to recurrence, especially early recurrence.
A relatively modern technique to effect hernia repair is to place a prosthetic mesh over the myopectineal orifice. This technique enlists the intra-abdominal pressure to secure the inlayed prosthesis to the pelvic floor rather than allowing it to act as a factor in recurrence of the hernia. After mesh placement, the peritoneum becomes nondistensible, so there is no need for hernia defect closure. An effective modification of this technique is to place a polypropylene mesh on the outside of the myopectineal orifice. The prosthesis is sutured to the adjacent tissues with a minimum of tension. This repair has proven effective in preventing both short- and long-term recurrence. In addition, the pain associated with this operation is less than with other open operations. Its single disadvantage is the required division of tissue to gain access. The operation is commonly performed under local anesthesia with sedation. Hospitalization is avoided and most patients return to work as rapidly as those experiencing the laparoscopic preperitoneal herniorrhaphy.
Several mechanisms of hernia recurrence have been identified, such as the use of an inadequately-sized prosthesis so that the entire myopectineal orifice is not covered. Related to this concept of an inadequately-sized mesh is the possibility of inadequate overlap. It is felt that all defects should be overlapped by at least 2 cm if the mesh is stapled and by 3 cm or more if not stapled. For example, the myopectineal orifice measures approximately 10 cmxc3x978 cm in an adult so a 16 cmxc3x9714 cm mesh is required.
While the placement of a prosthetic mesh in the preperitoneal space is currently performed with either a laparoscopic or an open technique, it is desirable to perform the procedure by placing small needle cannulas in the groin to dissect the preperitoneal space. Visualization would be obtained with a 2 mm laparoscope placed through one of the cannulas. The hernia sac would be dissected free and ligated. A prosthetic mesh would thereafter be placed to reinforce the transversalis fascia. The patient would have reduced pain and disability as currently is associated with the procedure. In addition, the need for general anesthesia could be eliminated.
Such a needle herniorrhaphy technique requires a device for creating an operating space in registry with the myopectineal orifice. The device should be insertable through the cannulus of a needle. The device should further be either retrievable through the cannulus of the needle after creating the operating space or biodegradable so that it may be left in place over the herniated region.
Such a needle herniorrhaphy technique also requires a prosthesis employing a thin surgical support mesh that may be rolled or folded and thereafter inserted within the cannulus of a needle. The mesh should also be non-linting, fray resistant, and ravel resistant. The mesh must be sufficiently porous to allow for tissue growth through the graft after implantation. The healing tissue grows through porous openings in the implanted mesh, thereby assimilating the mesh and adding structural integrity to the tissue.
The mesh is desirably self-opening upon emplacement over the myopectineal orifice. The mechanism for self-opening for the prosthesis must be reliable and should further provide suitable rigidity to the prosthesis in an open configuration, without unduly interfering with the anatomical members in the vicinity of the myopectineal orifice. Specifically, while the prosthesis should provide support to each side of the myopectineal orifice, the prosthesis should not interfere with, and risk closing of, the vas deferens. Additionally, the prosthesis should pose no risk of puncturing the peritoneum so as to induce infection.
It is therefore an object of the invention to provide a device for creating an operating space in registry with the herniated region of a patient.
It is another object of the invention to provide a device for delivering a surgical prosthetic mesh to operating space in registry with a herniated region of a patient.
It is yet another object of the present invention to provide a device for performing herniorrhaphy having a relatively small diameter so as to minimize the need for general anesthesia.
It is still yet another object of the invention to provide a mechanism for separating adjacent tissue layers within a patient so as to provide an operating space.
It is even still another object of the present invention to provide a mechanism for separating adjacent tissue layers within a patient that may delivered through a small diameter cannula.
It is yet even another object of the present invention to provide a mechanism which may be delivered through a small diameter cannula that will both separate adjacent tissue layers and deliver a prosthetic mesh to the operating space being created.
In the efficient attainment of these and other objects, the present invention provides an instrument for creating an operating space in a body in the form of an elongate blunt-nose cannula having an elongate side wall defining an access aperture, an interior lumen, and an elongate aperture. The cannula is deliverable along a guidewire between a first and second tissue layer in a body. The instrument also includes a retractable outer protective sheath, a fluid delivery lumen communicating with a fluid source, and a hollow expandable tissue separating balloon including a first major surface and a second major surface. The first major surface is peripherally contiguous with the second major surface and together the first and second major surfaces define a fluid-tight balloon cavity therebetween. The balloon cavity communicates with the fluid delivery lumen and is expandable through the elongate aperture of the cannula body from a first contracted configuration confined within the cannula body to a second expanded configuration extending through the elongate window. Expansion of the balloon thereby forces apart the adjacent first and second tissue layers so as to form the operating cavity.
The delivery cannula of the present invention is less than about 10 millimeters although diameters of between about 5 millimeters and 2 millimeters is desirable. Therefore the tissue separating balloons of the present invention are designed to have shapes which may be rolled, folded, or collapsed within a small diameter lumen. For example, several of the balloons of the present invention provide major surfaces with opposed tapering edges. The major surfaces of these balloons may be pleated, or alternately folded upon themselves, so as to effectively telescope outwardly from the stored configuration upon balloon inflation. The tapering edges minimize bunching up of the balloon material and thereby minimize the required mean diameter of the delivery cannula.
The cannula and balloon of the present invention are contemplated as providing for expansion of the balloon towards one side of the cannula. The cannula and balloon of the present invention are also contemplated as providing for expansion of the balloon towards two opposing sides of the cannula so as to centrally locate the guidewire in registry with the operating site being treated. Additionally, the balloon of the present invention may be formed to expand symmetrically about the cannula or in a longitudinally reversed symmetry so as to position the guidewire in registry with a diagonal axis of the operating space being treated.
Alternatively, the present invention provides a boundary balloon in that the balloon takes the form of a tubular wall having a substantially rectangular frame shape. In its fully inflated state the balloon is positioned only at the periphery of the created operating space. As it is not necessary to maintain the tissue layers apart once separated, a frame balloon provides for a maximum amount of space to be created for a given amount of balloon material. As less material is required to create an operating space, the diameter of the delivery cannula may be further reduced.
It is further contemplated that each of the balloons of the present invention may carry a porous surgical mesh so that upon expansion of the balloon the mesh will be unfurled over the operating site. The mesh may be detachable from the balloon so that the balloon may be withdrawn from the operating space once the mesh is emplaced. It is also contemplated that the balloon of the present invention may itself be detached from the fluid delivery lumen of the cannula so that the balloon may be left within with the mesh in registry with the operating space. Such a detachable balloon would be desirably formed from a bioabsorbable material.
In order to further minimize the required diameter of the cannula, the present invention also contemplates a detachable balloon having a major surface formed from a plugged porous surgical mesh. That is, the pores of the surgical mesh are plugged or filled so as to maintain the fluid integrity of the balloon during expansion by internal fluid pressure. However, the material used to fill the pores of the mesh will also be bioabsorbable so that as the filler material is absorbed by the body, the pores will be exposed so as to permit new tissue ingrowth therethrough. The remainder of the balloon is also formed from a bioabsorbable material. This balloon obviates the need for providing a major surface of the balloon simply to support a prosthetic mesh thereon and thereby decreases the required stored volume of the balloon and diameter of the delivery cannula.
The present invention also contemplates a device for creating an operating cavity in a mammal between two adjoining layers of tissue adjacent to an operating site on one of the tissue layers. The device includes an elongate hollow cannula defining an elongate interior lumen, an access port communicating with the interior lumen and accessible outside the body of a patient, and an elongate aperture also communicating with the interior lumen and accessible to the deployment area. The device includes a blunt nose for introducing the device into the body, and a guidewire-deliverable dissecting member which is deliverable within the interior lumen of the cannula to a deployment area adjacent to the operating site.
In one embodiment of the present invention, the cannula supports a dissecting member including an elongate dissecting tip transversely extendable from the elongate aperture of the dissecting member. The dissecting member further includes actuator means for retractably extending the dissecting tip from the dissecting member to separate layers of tissue adjacent the operating area to form the operating cavity. The dissecting tip is a substantially rigid member which will exhibit a minimum of deflection as it is extended between to the adjacent tissue layers so as to separate same.
The actuator means is desirably a pair of elongate push rods which extend and retract normally to the dissecting member and which may bend to negotiate a ninety degree turn so as to extend longitudinally through the cannula. The cannula desirably provides exclusive passageways for accommodating each push rod. The passageways are desirably conformally shaped to the outside surfaces of the push rods, which are desirably both rectangular. In order to minimize the buckling of the push rods as the dissecting tip is extended, the cannula passageways desirably impart a twist to the push rods so that deflection of the push rods will be directed against the adjacent tissue layers and not simply therebetween. A surgeon may apply light pressure from the outside of the patient to counteract the buckling of the push rods. Once the dissecting tip has been pushed to its maximum limit, the push rods may be retracted back through the cannula. If desired, especially where it is beneficial to centrally locate the guidewire within the operating space, the operator may rotate the cannula about the guidewire and extend the dissecting tip in the transversely-opposite direction so as to provide a larger operating cavity.
The present invention also contemplates providing a flexible wire within the cannula that has one end anchored to the blunt nose and the opposed free end extending through the lumen exterior of the patient. This embodiment further provides an elongate cannula window opening in one transverse direction towards the non-separated tissue layers. The flexible wire may be extended towards the blunt nose so as to buckle the wire outwardly through the cannula window so as to be forced between and to separate the adjacent tissue layers in order to form the operating cavity. The flexible wire may be formed having a cross-sectional shape which favors buckling towards the cannula window. The flexible wire may also have various projections on the surface thereof which facilitate tissue separation. Additionally, the cannula may provide a longitudinally centrally located protrusion formed on the cannula wall in facing opposition to the window and adjacent the flexible wire so as to instigate buckling of the wire towards the window. After retracting the flexible wire back into through the window, the operator may rotate the cannula about the guidewire until the window faces in the opposite transverse direction as before so as to provide an enlarged operating cavity with the guidewire centrally located in registry therewith. An alternate embodiment of this device provides a second elongate window communicating to the opposite direction as the first window and a second flexible wire similarly anchored to the blunt nose for extension through the second window so as to simultaneously form the enlarged operating space to either side of the guidewire.
The present invention further contemplates providing a tissue dissecting device within the cannula which is formed from a shape memory material and which has been deformed to be deliverable within the cannula to a location between two adjacent tissue layers in the body. The shape memory material is desirably activated by body temperature to assume a configuration where a tissue separating blade extends out through the cannula window and thereby separate the adjacent tissue layers. The extended blade is desirably longitudinally movable along the length of the window to create the desired operating space. The blade is desirably connected to an actuating rod extending through the lumen of the cannula outside the patient. An alternate embodiment of this device provides a second tissue separating blade formed from a shape memory material to extend in the opposite transverse direction so that the guidewire will be centrally located within the resulting operating cavity.
An even further embodiment of the present invention provides a pair of oppositely-extendable elongate blades having one end pivotally connected to a pivot pin carried at one end of an elongate support wire adjacent a blade stop surface. The opposite ends of the blades are transversely separated by a deployment wedge which is supported at the end of an elongate actuation wire. The deployment wedge includes a planar face in facing opposition to the blade stop surface. The actuation wire is extendable and retractable along the support wire. Retraction of the actuation wire retracts the deployment wedge which forces the blades to pivot outwardly from the cannula to separate the adjacent tissue layers. The blades transversely extend from the cannula when the planar face of the deployment wedge pins the blades against the blade stop surface. The operator may then axially extend both the actuation wire and the support wire so as to extend the tissue separating blades along the length of the cannula window and thereby form the operating cavity.
The present invention even further provides a device for delivering a surgical prosthetic mesh to a previously-formed operating space. The mesh delivery device includes an elongate cannula body having an elongate cannula cylindrical wall of a first outside diameter supporting an elongate cylindrical guidewire conduit having a second smaller outside diameter and an interior passageway for accommodating a guidewire. The distal end of the guidewire conduit supports a blunt nose including a cylindrical rim having the same diameter as the cylindrical cannula wall. The device defines a cylindrical cannula window, and a cylindrical mesh delivery area about the guidewire conduit, between the cannula cylindrical wall and the blunt nose. An elongate retractable sheath extends along the outside of the cylindrical cannula wall to the surface of the rim of the blunt nose. A prosthetic mesh is deployably wrapped about the guidewire conduit. The mesh may be wrapped by placing one edge of the mesh along the guidewire conduit and then furling the mesh about thereabout. Once the cannula is positioned within the operating cavity, the sheath is retracted to expose the prosthetic mesh. The free edge of the mesh may be grasped and transversely pulled to deploy the mesh within the operating space.
Alternatively, the mesh may be longitudinally folded so that the opposed edges of the mesh are brought towards each other. The crease is then place along the guidewire conduit. Furling the mesh about the guidewire conduit provides the opposed edges to either side of the guidewire conduit. The opposed edges may be simultaneously pulled in opposite directions to deploy the mesh within the operating space. This alternative delivery configuration for the mesh is advantageously employed when the guidewire is centrally located within the operating cavity.
The present invention also provides methods for employing the devices of the present invention.
The present invention will be more readily appreciated in a reading of the xe2x80x9cDetailed Description of the Preferred Embodimentsxe2x80x9d with reference to the drawings.